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 *
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 * in the documentation and/or other materials provided with the
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 * this software without specific prior written permission.
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#ifndef SKY_ENGINE_CORE_RENDERING_RENDERLAYERSTACKINGNODEITERATOR_H_
#define SKY_ENGINE_CORE_RENDERING_RENDERLAYERSTACKINGNODEITERATOR_H_

#include "flutter/sky/engine/wtf/Noncopyable.h"

namespace blink {

enum ChildrenIteration {
  NormalFlowChildren = 1,
  PositiveZOrderChildren = 1 << 1,
  AllChildren = NormalFlowChildren | PositiveZOrderChildren
};

class RenderLayerStackingNode;

// This iterator walks the RenderLayerStackingNode lists in the following order:
// NormalFlowChildren -> PositiveZOrderChildren.
class RenderLayerStackingNodeIterator {
  WTF_MAKE_NONCOPYABLE(RenderLayerStackingNodeIterator);

 public:
  RenderLayerStackingNodeIterator(const RenderLayerStackingNode& root,
                                  unsigned whichChildren)
      : m_root(root), m_remainingChildren(whichChildren), m_index(0) {}

  RenderLayerStackingNode* next();

 private:
  const RenderLayerStackingNode& m_root;
  unsigned m_remainingChildren;
  unsigned m_index;
};

// This iterator is similar to RenderLayerStackingNodeIterator but it walks the
// lists in reverse order (from the last item to the first one).
class RenderLayerStackingNodeReverseIterator {
  WTF_MAKE_NONCOPYABLE(RenderLayerStackingNodeReverseIterator);

 public:
  RenderLayerStackingNodeReverseIterator(const RenderLayerStackingNode& root,
                                         unsigned whichChildren)
      : m_root(root), m_remainingChildren(whichChildren) {
    setIndexToLastItem();
  }

  RenderLayerStackingNode* next();

 private:
  void setIndexToLastItem();

  const RenderLayerStackingNode& m_root;
  unsigned m_remainingChildren;
  int m_index;
};

}  // namespace blink

#endif  // SKY_ENGINE_CORE_RENDERING_RENDERLAYERSTACKINGNODEITERATOR_H_
